Various techniques for routing packets through communication networks are known in the art. Some known techniques select routing paths for packets based on the network state, e.g., traffic load or congestion. Such techniques are sometimes referred to as Adaptive Routing. AR techniques are described, for example, by Kim et al., in “Adaptive Routing in High-Radix Clos Network,” Proceedings of the 2006 ACM/IEEE Conference on Supercomputing (SC2006), Tampa, Fla., November 2006, which is incorporated herein by reference.
U.S. Patent Application Publication 2011/0096668, whose disclosure is incorporated herein by reference, describes a method for communication. A first packet, which belongs to a given packet flow, is routed over a first routing path through a communication network. A second packet, which follows the first packet in the given packet flow, is routed using a time-bounded Adaptive Routing (AR) mode, by evaluating a time gap between the first and second packets, routing the second packet over the first routing path if the time gap does not exceed a predefined threshold, and, if the time gap exceeds the predefined threshold, selecting a second routing path through the communication network that is potentially different from the first routing path, and routing the second packet over the second routing path.
Additional adaptive routing techniques for mitigating congestion are described by Minkenberg et al., in “Adaptive Routing in Data Center Bridges,” Proceedings of the 17th IEEE Symposium on High Performance Interconnects, August, 2009, which is incorporated herein by reference. Adaptive routing schemes for Converged Enhanced Ethernet (CEE) are described by Gusat et al., in “R3C2: Reactive Route & Rate Control for CEE,” Proceedings of the 18th IEEE Symposium on High Performance Interconnects, August, 2010, which is incorporated herein by reference.